This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 11-366758, filed Dec. 24, 1999, the entire contents of which are incorporated herein by reference.
The present invention relates to a disk drive having a system for performing head positioning control with the use of servo data recorded on a disk in particular.
Conventionally, in a hard disk drive (HDD), servo data is recorded on a disk used as a data recording medium. The servo data is used to control the positioning of a head to a target position (target cylinder or target track) over a disk. A servo area with.the servo data recorded thereon is such that, in many cylinders (also called as tracks) formed in a radial direction on the disk, the servo area is situated in the same position in the radial direction and at predetermined intervals in a circumferential direction. In other words, the many cylinders on the disk are formed with the servo data (servo area) used as a reference, the servo data being written by a servo write step included in the manufacturing process of the HDD.
It is desirable that, in order to increase a recording capacity in the HDD, as many cylinders as possible be formed on a restricted radial-direction data recording range on the disk by utilizing a high precision head positioning control system using the servo data.
In the manufacturing process of the HDD, the servo write step is carried out after a head disk assembly (HDA) has been incorporated into a drive body. In the servo write step, the servo data is recorded on the disk mounted on a spindle motor with the use of a dedicated device called as a servo track writer. The servo track writer has a means for detecting a head moving range defined by inner- and outer-circumference-side stoppers mounted on a drive body and it is possible to set a radial area corresponding to an effective data recording area on the disk. It is, therefore, possible to set the radial area corresponding to the effective data recording area on the disk so as to conform to an assembling accuracy of a drive mechanism such as an HDA.
In order to achieve a high efficiency of the HDD assembling process and an increased recording capacity of the disk, it is desirable that a disk with servo data initially recorded thereon be incorporated into the drive mechanism. In this case, there is no servo write process and the disk is prepared with the servo data already recorded thereon, so that the disk be incorporated into the drive body in the assembling step of the drive mechanism.
In this method, however, it is necessary to take, into consideration, a variation arising from the assembling accuracy of the drive mechanism such as an HDA. If, therefore, the radial area is set in a way to correspond to the effective data recording area on the disk, a margin has to be provided, so that an actually utilizable data recording area is restricted. Even if, therefore, the servo data is recorded on the disk before the step of an assembly into the drive body so as to increase the effective data recording area, an actually available data recording area is restricted, thus making it difficult to achieve an increased memory capacity.
It is accordingly the object of the present invention to provide a disk drive which, even if the method of assembling a disk with servo data initially recorded thereon into a drive mechanism is adopted, can easily achieve an increased recording capacity.
According to the present invention there is provided a disk drive comprising: a disk having a cylinder group in a radial direction, each cylinder having a data area recorded with data and servo area initially recorded with physical cylinder address information for identifying the cylinder; a head actuator for holding a head for reading and writing data from and into the disk and moving the head to a target position on the disk; generating means for setting an effective cylinder group contained from the cylinder group and generating logical cylinder address information so defined as to correspond to the physical cylinder address information for identifying each cylinder contained in the effective cylinder group; and control means for, when the head is positioned to a target position on the disk, allowing the generating means to find first physical cylinder address information corresponding to the target position with the use of the logical cylinder access information corresponding to the target position and allowing the driving control of the head actuator so as to be equal the first physical cylinder address information and second physical cylinder address information read out by the head from the disk.
According to the disk drive thus structured, after the disk with servo data initially recorded thereon has been incorporated into the drive mechanism, it is possible to set the effective data recording range on the disk so as to conform to the accuracy, etc., of the drive mechanism. That is, based on the initially recorded servo data, many cylinder groups are formed in the radial direction on the disk. These many cylinder groups can be identified by the physical cylinder address information contained in the servo data. From the many cylinder groups, the effective cylinder group contained in the effective data recording range is set and the logical cylinder address information is allocated so as to identify each cylinder in the effective cylinder group. That is, the logical cylinder address information is so defined as to correspond to the physical cylinder address information for identifying each cylinder contained in the effective cylinder group.
The disk drive of the present invention controls the effective cylinder group on the disk with the use of the logical cylinder address information. In the head positioning control at a data access time, the control means finds first physical cylinder address information corresponding to the target position with the use of the logical cylinder address information corresponding to the target position of the head. Further, the control means performs driving control of the head actuator on the basis of the first physical cylinder address information and second physical cylinder address information read out by the head from the disk and locates the head to the target position.
According to the present invention, if the disk with the servo data initially recorded thereon is incorporated into the drive body, it is not necessary to take, into consideration, a margin for a variation in assembling accuracy of the drive mechanism. That is, an effective cylinder group contained in the effective data recording range is set from the cylinder group on the disk in accordance with the assembling accuracy of the actual drive mechanism. By doing so, it is possible to set a maximal-limit effective cylinder group from the cylinder group on the disk and promote an increased memory capacity. Since it is possible to use the disk having the servo data initially recorded thereon, it is possible to achieve an improved efficiency of a disk drive assembling process.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.